NITROGEN FERTILIZER USE EFFICIENCY AND GHG EMISSIONS IN THE LATVIAN GRAIN SECTOR.

The agricultural sector has shown a stable and steady growth in Latvia, and the year 2015 was the most successful for Latvian grain growers. The largest grain harvest was collected that year. Nitrogen (N), phosphorous (P) and potassium (K) fertilizers are an essential factor that determines the quantity and quality of the crops harvested. However, over-fertilization can lead to negative economic and environmental consequences such as high production costs, depletion of energy resources and increased greenhouse gas (GHG) emissions. Emissions from agricultural soils contributed to the major share of the total emissions from the sector - 53.7 %. N (pure nitrogen content) fertilizer application management is essential in improving the mentioned indicators. Traditionally, N fertilizers have been applied uniformly across the entire field while ignoring inherent spatial variation in the crop N needs within the crop fields. This results in either too little or too much application of N in various parts of the fields. Too little N reduces the yields, while too much N reduces the nitrogen use efficiency (NUE). The aim of the research study is to examine the opportunities to reduce direct N2O emissions from N (nitrogen content) fertiliser application in crop farming using the constant and variable N fertiliser spreading technologies. In the present research study, the authors have carried out an N fertilizer efficiency assessment to understand the evolution of cereal production in Latvia by using precision farming experimental data. Suitable qualitative and quantitative research methods were applied in the research. The research found that the use of the variable N fertiliser spreading technology led to a decrease in the consumption of N (pure nitrogen) fertilisers, as the average fertiliser application rate in the case of variable fertiliser spreading decreased by 10 kg.ha-1, which, in its turn, reduced CO2 emissions by 46.8 kg.ha-1. [ABSTRACT FROM AUTHOR]